Laminated glass having a structure in which a pair of glass plates are bonded together by an intermediate bonding layer to be integrated is generally manufactured in such a manner that a resin intermediate film is sandwiched by a pair of glass plates to form a glass laminate, and this is subjected to high temperature and high pressure processing in an autoclave or the like. By this method, the pair of glass plates is bonded by heat sealing of the resin intermediate film to be the laminated glass.
As a technique to impart various kinds of functions such as infrared blocking to such laminated glass, there is known a technique in which two resin intermediate films with a plastic film having these functions therebetween are inserted between a pair of glass plates to bond the pair of glass plates by heat sealing similarly to the above. In this case, before being combined with the glass plates and subjected to high-temperature and high-pressure processing, the plastic film and the resin intermediate films are integrated in advance by compression bonding or the like to be a composite film. In some case, the composite film is prepared as a three-layer composite film in which the plastic film is sandwiched by two resin intermediate films, but is often prepared as a two-layer composite film in which the plastic film is laminated on one resin intermediate film.
The resin intermediate film and the plastic film are prepared as, for example, long scrolls in consideration of productivity, and are continuously subjected to roll compression bonding by a laminating apparatus or the like to be the composite film. However, the resin intermediate film used for manufacturing the laminated glass elongates when given a certain level of tension or more due to its property and when it is compression-bonded with the plastic film in this state, there occur problems such as that the resin intermediate film in the obtained composite film contracts to curl or the resin intermediate film peels off from the plastic film. Further, the resin intermediate film has problems of being likely to wrinkle during the roll compression boding if its tension is low, and losing emboss that the resin intermediate film usually has on its surface if being subjected to high-temperature compression bonding.
On the other hand, Patent Reference 1 (WO 2009/154060 A1) describes a method in which, in a case where laminated glass in which a plastic film is inserted similarly to the above and which uses glass plates formed in a curved shape is manufactured, resin intermediate films and the plastic film are bonded by pressing and heating to be a composite film after being laminated at a 10 to 25° C. temperature range for the purpose of preventing the plastic film from wrinkling. Incidentally Patent Reference 1 makes no mention of the aforesaid problem which occurs in manufacturing the composite film for laminated glass due to a load applied to the resin intermediate film.